ardupilot/libraries/AP_Mount/AP_Mount_CADDX.cpp

#include "AP_Mount_config.h"

#if HAL_MOUNT_CADDX_ENABLED

#include "AP_Mount_CADDX.h"
#include <AP_HAL/AP_HAL.h>

#define AP_MOUNT_CADDX_RESEND_MS   1000    // resend angle targets to gimbal once per second
#define SET_ATTITUDE_HEADER1 0xA5
#define SET_ATTITUDE_HEADER2 0x5A
#define SET_ATTITUDE_BUF_SIZE 10
#define AXIS_MIN 0
#define AXIS_MAX 4096

// update mount position - should be called periodically
void AP_Mount_CADDX::update()
{
    // exit immediately if not initialised
    if (!_initialised) {
        return;
    }

    // change to RC_TARGETING mode if RC input has changed
    set_rctargeting_on_rcinput_change();

    // flag to trigger sending target angles to gimbal
    bool resend_now = false;

    // update based on mount mode
    switch (get_mode()) {
        // move mount to a "retracted" position.  To-Do: remove support and replace with a relaxed mode?
        case MAV_MOUNT_MODE_RETRACT: {
            const Vector3f &target = _params.retract_angles.get();
            mnt_target.angle_rad.set(target*DEG_TO_RAD, false);
            mnt_target.target_type = MountTargetType::ANGLE;
            break;
        }

        // move mount to a neutral position, typically pointing forward
        case MAV_MOUNT_MODE_NEUTRAL: {
            const Vector3f &target = _params.neutral_angles.get();
            mnt_target.angle_rad.set(target*DEG_TO_RAD, false);
            mnt_target.target_type = MountTargetType::ANGLE;
            break;
        }

        // point to the angles given by a mavlink message
        case MAV_MOUNT_MODE_MAVLINK_TARGETING:
            // mnt_target should have already been filled in by set_angle_target() or set_rate_target()
            if (mnt_target.target_type == MountTargetType::RATE) {
                update_angle_target_from_rate(mnt_target.rate_rads, mnt_target.angle_rad);
            }
            resend_now = true;
            break;

        // RC radio manual angle control, but with stabilization from the AHRS
        case MAV_MOUNT_MODE_RC_TARGETING: {
            // update targets using pilot's RC inputs
            update_mnt_target_from_rc_target();
            resend_now = true;
            break;
        }

        // point mount to a GPS point given by the mission planner
        case MAV_MOUNT_MODE_GPS_POINT:
            if (get_angle_target_to_roi(mnt_target.angle_rad)) {
                mnt_target.target_type = MountTargetType::ANGLE;
                resend_now = true;
            }
            break;

        // point mount to Home location
        case MAV_MOUNT_MODE_HOME_LOCATION:
            if (get_angle_target_to_home(mnt_target.angle_rad)) {
                mnt_target.target_type = MountTargetType::ANGLE;
                resend_now = true;
            }
            break;

        // point mount to another vehicle
        case MAV_MOUNT_MODE_SYSID_TARGET:
            if (get_angle_target_to_sysid(mnt_target.angle_rad)) {
                mnt_target.target_type = MountTargetType::ANGLE;
                resend_now = true;
            }
            break;

        default:
            // we do not know this mode so do nothing
            break;
    }

    // resend target angles at least once per second
    resend_now = resend_now || ((AP_HAL::millis() - _last_send_ms) > AP_MOUNT_CADDX_RESEND_MS);
    if (resend_now) {
        send_target_angles(mnt_target.angle_rad);
    }
}

// get attitude as a quaternion.  returns true on success
bool AP_Mount_CADDX::get_attitude_quaternion(Quaternion& att_quat)
{
    // gimbal does not provide attitude so simply return targets
    att_quat.from_euler(mnt_target.angle_rad.roll, mnt_target.angle_rad.pitch, mnt_target.angle_rad.get_bf_yaw());
    return true;
}

// send_target_angles
void AP_Mount_CADDX::send_target_angles(const MountTarget& angle_target_rad)
{
    // exit immediately if not initialised
    if (!_initialised) {
        return;
    }

    // ensure we have enough space to send the packet
    if (_uart->txspace() < SET_ATTITUDE_BUF_SIZE) {
        return;
    }

    // calculate roll, pitch, yaw angles in range 0 to 4096
    const float scalar = AXIS_MAX / M_2PI;
    const uint16_t roll_target_cmd = constrain_uint16(wrap_2PI(angle_target_rad.roll) * scalar, AXIS_MIN, AXIS_MAX);
    const uint16_t pitch_target_cmd = constrain_uint16(wrap_2PI(angle_target_rad.pitch) * scalar, AXIS_MIN, AXIS_MAX);
    const uint16_t yaw_target_cmd = constrain_uint16(wrap_2PI(angle_target_rad.get_bf_yaw()) * scalar, AXIS_MIN, AXIS_MAX);

    // prepare packet to send to gimbal
    uint8_t set_attitude_cmd_buf[SET_ATTITUDE_BUF_SIZE] {};

    // first two bytes hold the header
    set_attitude_cmd_buf[0] = SET_ATTITUDE_HEADER1;
    set_attitude_cmd_buf[1] = SET_ATTITUDE_HEADER2;

    // byte 2's lower 3 bits are mode
    // lower 5 bits are sensitivity but always left as zero
    uint8_t mode = (uint8_t)LockMode::TILT_LOCK | (uint8_t)LockMode::ROLL_LOCK;
    if (angle_target_rad.yaw_is_ef) {
        mode |= (uint8_t)LockMode::YAW_LOCK;
    }
    set_attitude_cmd_buf[2] = mode & 0x07;

    // byte 3's lower 4 bits are reserved
    // upper 4 bits are roll's lower 4 bits
    set_attitude_cmd_buf[3] = (roll_target_cmd << 4) & 0xF0;

    // byte 4 is roll's upper 8 bits
    set_attitude_cmd_buf[4] = (roll_target_cmd >> 4) & 0xFF;

    // byte 5 is pitch's lower 8 bits
    set_attitude_cmd_buf[5] = pitch_target_cmd & 0xFF;

    // byte 6's lower 4 bits are pitch's upper 4 bits
    // upper 4 bits are yaw's lower 4 bits
    set_attitude_cmd_buf[6] = (pitch_target_cmd >> 8) & 0x0F;
    set_attitude_cmd_buf[6] |= (yaw_target_cmd << 4) & 0xF0;

    // byte 7 is yaw's upper 8 bits
    set_attitude_cmd_buf[7] = (yaw_target_cmd >> 4) & 0xFF;

    // calculate CRC
    const uint16_t crc16 = crc16_ccitt(set_attitude_cmd_buf, sizeof(set_attitude_cmd_buf) - 2, 0);
    set_attitude_cmd_buf[8] = HIGHBYTE(crc16);
    set_attitude_cmd_buf[9] = LOWBYTE(crc16);

    // send packet to gimbal
    _uart->write(set_attitude_cmd_buf, sizeof(set_attitude_cmd_buf));

    // store time of send
    _last_send_ms = AP_HAL::millis();
}

#endif // HAL_MOUNT_CADDX_ENABLED